TAO_Singleton_Manager.cpp

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// $Id: TAO_Singleton_Manager.cpp 79958 2007-11-09 09:04:45Z johnnyw $

#include "tao/TAO_Singleton_Manager.h"

#include "ace/Guard_T.h"
#include "ace/Recursive_Thread_Mutex.h"
#include "ace/Log_Msg.h"
#include "ace/Object_Manager.h"

#if !defined (__ACE_INLINE__)
# include "tao/TAO_Singleton_Manager.inl"
#endif /* ! __ACE_INLINE__ */

ACE_RCSID (tao,
           TAO_Singleton_Manager,
           "$Id: TAO_Singleton_Manager.cpp 79958 2007-11-09 09:04:45Z johnnyw $")

namespace
{
  // Singleton instance pointer.
  TAO_Singleton_Manager * the_instance = 0;
}

#if (defined (ACE_HAS_VERSIONED_NAMESPACE) && ACE_HAS_VERSIONED_NAMESPACE == 1)
# define TAO_SINGLETON_MANAGER_CLEANUP_DESTROYER_NAME ACE_PREPROC_CONCATENATE(TAO_VERSIONED_NAMESPACE_NAME, _TAO_Singleton_Manager_cleanup_destroyer)
#endif  /* ACE_HAS_VERSIONED_NAMESPACE == 1 */

// Adapter for cleanup, used to register cleanup function with the
// ACE_Object_Manager.
extern "C" void
TAO_SINGLETON_MANAGER_CLEANUP_DESTROYER_NAME (void *, void *)
{
#if defined (TAO_HAS_VERSIONED_NAMESPACE) \
    && TAO_HAS_VERSIONED_NAMESPACE == 1
  using namespace TAO_VERSIONED_NAMESPACE_NAME;
#endif  /* TAO_HAS_VERSIONED_NAMESPACE */

  if (the_instance)
    {
      (void) TAO_Singleton_Manager::instance ()->fini ();
    }
}

TAO_BEGIN_VERSIONED_NAMESPACE_DECL

TAO_Singleton_Manager::TAO_Singleton_Manager (void)
  // default_mask_ isn't initialized, because it's defined by <init>.
  : thread_hook_ (0),
    exit_info_ (),
    registered_with_object_manager_ (-1)
#if defined (ACE_MT_SAFE) && (ACE_MT_SAFE != 0)
    , internal_lock_ (0)
# endif /* ACE_MT_SAFE */
{
#if defined (ACE_MT_SAFE) && (ACE_MT_SAFE != 0)
  ACE_NEW (this->internal_lock_,
           TAO_SYNCH_RECURSIVE_MUTEX);
# endif /* ACE_MT_SAFE */
  // Be sure that no further instances are created via instance ().
  if (the_instance == 0)
    {
      the_instance = this;
    }

  // @@ This is a hack.  Allow the TAO_Singleton_Manager to be registered
  //    with the ACE_Object_Manager (or not) in an explicit call to
  //    TAO_Singleton_Manager::init().  However, once the explicit call is
  //    made, it will not be possible to alter the setting.
  int register_with_object_manager = -1;
  (void) this->init (register_with_object_manager);
}

TAO_Singleton_Manager::~TAO_Singleton_Manager (void)
{
  this->dynamically_allocated_ = false;   // Don't delete this again in fini()
  (void) this->fini ();
}

sigset_t *
TAO_Singleton_Manager::default_mask (void)
{
  return TAO_Singleton_Manager::instance ()->default_mask_;
}

ACE_Thread_Hook *
TAO_Singleton_Manager::thread_hook (void)
{
  return TAO_Singleton_Manager::instance ()->thread_hook_;
}

ACE_Thread_Hook *
TAO_Singleton_Manager::thread_hook (ACE_Thread_Hook *new_thread_hook)
{
  TAO_Singleton_Manager *tao_om = TAO_Singleton_Manager::instance ();
  ACE_Thread_Hook *old_hook = tao_om->thread_hook_;
  tao_om->thread_hook_ = new_thread_hook;
  return old_hook;
}

TAO_Singleton_Manager *
TAO_Singleton_Manager::instance (void)
{
  // This function should be called during construction of static
  // instances, or before any other threads have been created in the
  // process.  So, it's not thread safe.

  if (the_instance == 0)
    {
      TAO_Singleton_Manager *instance_pointer = 0;

      ACE_NEW_RETURN (instance_pointer,
                      TAO_Singleton_Manager,
                      0);
      ACE_ASSERT (instance_pointer == the_instance);

      instance_pointer->dynamically_allocated_ = true;

      return instance_pointer;
    }
  else
    {
      return the_instance;
    }
}

int
TAO_Singleton_Manager::init (void)
{
  if (this->registered_with_object_manager_ == -1)
    {
      // Register the TAO_Singleton_Manager with the
      // ACE_Object_Manager.
      int register_with_object_manager = 1;

      return this->init (register_with_object_manager);
    }

  return 1;  // Already initialized.
}

int
TAO_Singleton_Manager::init (int register_with_object_manager)
{
  if (this->starting_up_i ())
    {
      // First, indicate that this TAO_Singleton_Manager instance is being
      // initialized.
      this->object_manager_state_ = OBJ_MAN_INITIALIZING;

      if (this == the_instance)
        {
# if defined (ACE_MT_SAFE) && (ACE_MT_SAFE != 0)
          // @@ No MT-specific pre-allocated objects.
# endif /* ACE_MT_SAFE */
        }

      ACE_NEW_RETURN (this->default_mask_, sigset_t, -1);
      ACE_OS::sigfillset (this->default_mask_);

      // Finally, indicate that the TAO_Singleton_Manager instance has
      // been initialized.
      this->object_manager_state_ = OBJ_MAN_INITIALIZED;

      return 0;
    }

  // @@ This strange looking code is what provides the "register on
  //    explicit call to init()" semantics.  This was needed since the
  //    TAO_Singleton_Manager constructor invokes init().
  //    Unfortunately, I couldn't get rid of that init() call without
  //    breaking things.  The fact things broke needs to be
  //    investigated further.
  if (this->registered_with_object_manager_ != -1
      && register_with_object_manager != this->registered_with_object_manager_)
    {
      // An attempt was made to register the TAO_Singleton_Manager
      // with a manager of a different type from the one it is
      // currently registered with.  This indicates a problem with the
      // caller's logic.

      errno = EINVAL;
      return -1;
    }

  if (this->registered_with_object_manager_ == -1)
    {
      if (register_with_object_manager == 1
          && ACE_Object_Manager::at_exit (
               this,
               (ACE_CLEANUP_FUNC) TAO_SINGLETON_MANAGER_CLEANUP_DESTROYER_NAME,
               0) != 0)
        return -1;

      this->registered_with_object_manager_ =
        register_with_object_manager;
    }

  // Had already initialized.
  return 1;
}

// Clean up a TAO_Singleton_Manager.  There can be instances of this object
// other than The Instance.  This can happen if a user creates one for some
// reason.  All objects clean up their per-object information and managed
// objects, but only The Instance cleans up the static preallocated objects.

int
TAO_Singleton_Manager::fini (void)
{
  if (the_instance == 0  ||  this->shutting_down_i ())
    // Too late.  Or, maybe too early.  Either fini () has already
    // been called, or init () was never called.
    return this->object_manager_state_ == OBJ_MAN_SHUT_DOWN  ?  1  :  -1;

  // No mutex here.  Only the main thread should destroy the singleton
  // TAO_Singleton_Manager instance.

  // Indicate that the TAO_Singleton_Manager instance is being shut
  // down.  This object manager should be the last one to be shut
  // down.
  this->object_manager_state_ = OBJ_MAN_SHUTTING_DOWN;

  // If another Object_Manager has registered for termination, do it.
  if (this->next_)
    {
      this->next_->fini ();
      this->next_ = 0;  // Protect against recursive calls.
    }

  // Call all registered cleanup hooks, in reverse order of
  // registration.
  this->exit_info_.call_hooks ();

//   // Only clean up preallocated objects when the singleton Instance is being
//   // destroyed.
//   if (this == the_instance)
//     {
// #if ! defined (ACE_HAS_STATIC_PREALLOCATION)
//       // Cleanup the dynamically preallocated objects.
// # if defined (ACE_MT_SAFE) && (ACE_MT_SAFE != 0)
//       // @@ No MT-specific preallocated objects yet.
// # endif  /* ACE_MT_SAFE */
//       // @@ No preallocated objects yet.
// #endif  /* ! ACE_HAS_STATIC_PREALLOCATION */
//     }

  delete this-> default_mask_;
  this->default_mask_ = 0;

#if defined (ACE_MT_SAFE) && (ACE_MT_SAFE != 0)
  delete this->internal_lock_;
  this->internal_lock_ = 0;
#endif /* ACE_MT_SAFE */

  // Indicate that this TAO_Singleton_Manager instance has been shut down.
  this->object_manager_state_ = OBJ_MAN_SHUT_DOWN;

  if (this == the_instance)
    the_instance = 0;

  if (this->dynamically_allocated_)
    {
      delete this;
    }

  return 0;
}

int
TAO_Singleton_Manager::starting_up (void)
{
  return
    the_instance
    ? the_instance->starting_up_i ()
    : 1;
}

int
TAO_Singleton_Manager::shutting_down (void)
{
  return
    the_instance
    ? the_instance->shutting_down_i ()
    : 1;
}

int
TAO_Singleton_Manager::at_exit_i (void *object,
                                  ACE_CLEANUP_FUNC cleanup_hook,
                                  void *param)
{
  ACE_MT (ACE_GUARD_RETURN (TAO_SYNCH_RECURSIVE_MUTEX,
                            ace_mon,
                            *the_instance->internal_lock_,
                            -1));

  if (this->shutting_down_i ())
    {
      errno = EAGAIN;
      return -1;
    }

  if (this->exit_info_.find (object))
    {
      // The object has already been registered.
      errno = EEXIST;
      return -1;
    }

  return this->exit_info_.at_exit_i (object, cleanup_hook, param);
}

TAO_END_VERSIONED_NAMESPACE_DECL

---